Journal: PLoS Biology

Article Title: Chrna2-Martinotti Cells Synchronize Layer 5 Type A Pyramidal Cells via Rebound Excitation

doi: 10.1371/journal.pbio.2001392

Figure Lengend Snippet: (A) Confocal image (20 μm, coronal slice) of primary auditory cortex of a Chrna2-Cre/R26 tom mouse showing tdTomato+ somas (red) in L5 with dense axonal arborizations in layer 1 (arrow in corner, scale bar = 100 μm). (B) Confocal image and tracing of a biocytin-filled tdTomato+ neuron (green). Reconstruction of soma and dendrites (black) and axon (red; scale bar = 20 μm) shows long axonal projections to layer 1. (C) Confocal images of a biocytin-filled (green) tdTomato+ neuron among several tdTomato+ neurons (red) show that cells have an ovoid cell body in L5, bipolar dendritic morphology, and proximal axonal arborizations. (D) Image illustrating how the Chrna2-Cre/R26 tom axons emerge from the main dendrite (circle). Scale bars = 50 μm. (E) Image showing the long axonal arborizations (arrows) from one biocytin-filled Chrna2-Cre/R26 tom cell (yellow) to layer 1 and the dense axonal ramifications (asterisk) in layer 1 from all Chrna2-Cre/R26 tom cells expressing tdTomato (red). Scale bars = 50 μm. (F) Example from another biocytin-filled Chrna2-Cre/R26 tom cell to emphasize axonal arborization extending laterally in layer 1, seen as a thin yellow axon at the border of the axonal plexus of Chrna2-Cre/R26 tom cell in layer 1. (G) Top : Example current clamp traces from a tdTomato+ cell showing low-threshold, accommodating firing (20 pA response in red, 100 pA in black, 500 ms) and rebound APs (−20 to −80 pA, 500 ms) typical for Martinotti cells. Bottom : Current clamp trace in response to a 200-pA, 1,000-ms-long stimulus used for analysis in (H). (H) Left : The frequency/current (f/I) curve of MCs α2 shows an average firing rate around 20 Hz (at 200 pA, 1,000 ms) indicating slow spiking properties. Middle : Difference in maximum frequency and steady-state frequency for each neuron to a 200 pA, 1,000-ms-long current step highlights an accommodating discharge. The black line depicts the mean adaptation. Right : Spike-frequency adaptation is shown as a function of time. Data ( n = 36 cells) are presented as mean ± standard error of the mean (SEM) and shown in .

Article Snippet: Chrna2-Cre/ R26 tom cells were counted using Imaris 8.1 (Bitplane) and Matlab (version 2013a, MathWorks) in an 800-μM section (AP: −2.40 to −3.20 mm, ML: 2.00 to 5.00 mm, and DV: 0.50 to 3.50 mm).

Techniques: Expressing